1. Field of the Invention
The present invention relates to a method for internally lining ducts, said lining being in the form of a self supporting sleeve.
2. Description of the Prior Art
A method is known for lining ducts which is characterized in that a sleeve permeable over at least a part of its thickness to a heat hardenable resin, such as an epoxy resin, is introduced into the duct, said sleeve being able to enlarge its section under the action of a pressure exerted on its internal wall and thus being able to adapt its section to that of the duct, without the composite material used for said sleeve undergoing an elastic or plastic deformation; the pressure on the internal sleeve, in this known method, is exerted via an inflatable balloon until the external wall of said sleeve is applied against the internal wall of said duct, and it is held until the resin hardens, the pressure and the temperature of the fluid for inflating the baloon being controlled during the while operation. After hardening of the resin, said balloon is deflated and removed. In this known method, a composite material is used which may be entirely permeable to a heat hardenable resin, such for example as a material formed by at least an assembly comprising a first layer in the form of a framework, for example in the form of a woven glass fiber fabric; a second layer made from a non woven material such as a glass mat; and a third layer in the form of a framework, for example in the form of a woven glass fiber fabric.
Such a process and such a composite material are known from the French patents 82 12 732 of the 21 July 1982 and 83 08 918 of the 30 May 1983 in the names of the applicant.
The aim of the present invention is to improve and simplify the above described method while making it more reliable.